As representative of photosensitive materials which can be solubilized by irradiation with actinic rays, that is to say, which can work positively, orthoquinonediazide compounds have so far been known, and in practice they have been widely used in lithographic printing plates, photoresists and so on. Such orthoquinonediazide compounds are described, for example, in U.S. Pat. Nos. 2,766,118, 2,767,092, 2,772,972, 2,859,112, 2,907,665, 3,046,110, 3,046,111, 3,046,115, 3,046,118, 3,046,119, 3,046,120, 3,046,121, 3,046,122, 3,046,123, 3,061,430, 3,102,809, 3,106,465, 3,635,709 and 3,647,443, and in a number of publications.
When irradiated with actinic rays, these orthoquinonediazide compounds decompose to produce carboxylic acids of 5-membered rings, whereby they become alkali-soluble. This property enables the orthoquinonediazide compounds to be used as positively working photosensitive materials. However, such orthoquinonediazide compounds have the defect that their photosensitivities are insufficient. This is because the quantum yield in the photochemical reaction of orthoquinonediazide compounds is essentially less than 1.
For the purpose of enhancing photosensitivities of photosensitive compositions containing orthoquinonediazide compounds, various methods have been attempted. However, it has been very difficult to increase the photosensitivities of such compositions, while retaining their development latitudes. For instance, such attempts are described in U.S. Pat. No. 3,661,582 (German Patent Application (OLS) No. 2,028,214), U.S. Pat. Nos. 4,009,003, 4,307,173 and so on.
Recently, some photosensitive compositions which can work positively without containing orthoquinonediazide compounds have been proposed. One of them, for example, contains a polymer compound having an orthonitrocarbinol ester group, as described in U.S. Pat. No. 3,849,137 (German Patent Application (OLS) No. 2,150,691). In this case also, however, the photosensitivity is insufficient for the same reason as in the case of an orthoquinonediazide. Aside from such a composition, there have been proposed photosensitive systems which can be activated by catalytic action. Therein, the photosensitivity can be enhanced by application of the principle that an acid produced upon photolysis brings about a second reaction, whereby the exposed portions are solubilized.
As examples of such photosensitive systems, mention may be made of a combination of a compound capable of producing an acid by photolysis with an acetal or O,N-acetal compound (U.S. Pat. No. 3,779,778), a combination of a compound capable of producing an acid upon photolysis with an orthoester or amidoacetal compound (U.S. Pat. No. 4,101,323), a combination of a compound capable of producing an acid by photolysis with a polymer having an acetal or ketal group in its main chain (U.S. Pat. No. 4,247,611), a combination of a compound capable of producing an acid by photolysis with an enol ether compound (U.S. Pat. No. 4,248,957), a combination of a compound capable of producing an acid by photolysis with an N-acyliminocarboxylic acid compound (U.S. Pat. No. 4,250,247), and a combination of a compound capable of producing an acid by photolysis with a polymer having an orthoester group in its main chain (U.S. Pat. No. 4,311,782). These combinations have the possibility of exhibiting high photosensitivities because they can have quantum yields of more than 1, in principle. However, in the case of the acetal or O,N-acetal compound, and in the case of the polymer having an acetal or ketal group in its main chain, the second reaction caused by the acid produced upon photolysis proceeds so slowly that photosensitivity high enough to be fit for practical use cannot be achieved. On the other hand, although photosensitivities attained are undoubtedly high in the cases of the orthoester or amidoacetal compound, the enol ether compound, and the N-acyliminocarboxylic acid compound, these compounds are poor in stability with a lapse of time and cannot be preserved for a long period of time. Further, the combination with the polymer having an orthoester group in its main chain, though highly photosensitive, suffers from the defect that its development latitude is rather narrow.